Distinguish what a thing is from the fact that it exists.
An essence considered in itself is neither one nor many, neither universal nor particular; existence does not follow from it, so every caused being receives its existence from something other than itself.
Avicenna’s formula that horseness is just horseness means that being one horse or a universal is added to the essence, not contained in it.
Every being is either possible in itself, needing a cause, or necessary through itself; since a chain of possible beings taken as a whole is still possible, it depends on one uncaused Necessary Existent, simple, whose essence is nothing other than its existence.
However long a chain of borrowed lights may be, nothing in it would shine unless some light shone by itself.
Imagine a person created all at once in empty air, sight veiled, limbs held apart, feeling nothing of his body: he would still affirm that he exists, so the self that knows itself is not the body or any of its parts.
In total darkness and silence, a waking person knows that she exists before checking whether she has hands or feet.
The last of the celestial intellects gives forms to sublunary matter and illuminates human minds; study prepares the soul, and grasping an intelligible is a contact with this giver of forms, not a mere sum of sensations.
After working through many cases, a student suddenly sees the general rule; Avicenna calls the power that hits on the middle term at once intuition.